Esters of nitroalcohols



Patented Nov. 22, 1949 ESTERS F NITROALCOHOLS John B. Tindall, Terre Haute,

Ind., assignor to Commercial Solvents Corporation, Terre Haute, 11141., a corporation of Maryland No Drawing. Application June 2, 1944, Serial No. 538,526

1 Claim.

This invention relates to a new series of compounds useful as impregnating agents for imparting water repellency to fabrics and the like. More particularly my invention is concerned with certain higher aliphatic acid esters of nitroalcohols produced by the interaction of an aliphatic acid or an anhydride thereof, with an aliphatic nitroalcohol, said esters having the following general structural formula:

wherein R R and R may be either hydrogen or alkyl and R represents an alkyl group having from eleven to seventeen carbon atoms inclusive. The above generic formula includes such compounds as 2-nitro-1-butyl stearate; 2-nitro-2- methyl-l-propyl stearate; 2-nitro-2-methyl-1- propyl palmitate, 2-nitro propyl stearate and the like.

In the preparation of waterproof and water repellent fabrics, it is customary to treat the raw fabric with solutions containing relatively small quantities of agents which will adhere to the fabric fibers. The fabrics are thereafter subjected to a baking or ironing process in which the water repellent quality of the treated fabric is developed inv some manner not completely understood, possibly by causing the impregnant to flow around: fibers and to seal off the. capillary the aliphatic acid or anhydride, the reaction mixture is maintained at a temperature of from 40 C. to not insubstantial excess of 100 0., and

preferably Within the range of 50-90 0., said temperature range being maintained by means of external cooling, if necessary.

When an aliphatic acid is employed in esterifying the nitroalcohol, the reaction is found to be greatly facilitated by the presence of an organic liquid, such as benzene, toluene, xylene, or the like, which is capable of removing the water formed during the esterification reaction,

as a constant boiling mixture. Upon completionv of the reaction, as may be evidenced by the removal of approximately the theoretical amount of waterformed, the crude reaction mixture is first subjected to distillation under a vacuum of approximately -150 mm., to remove the benzene or similar liquid, if employed, and the still residue thus obtained is further rectified under a relatively high vacuum, to recover the ester in a substantially pure state.

When employing the acid anhydride, the procedure of recovering the ester of the nitro alcohol differs slightly from that described above in that I have found it preferable to add to the reaction mixture a small quantity of a lower aliphatic alcohol such as methanol or ethanol after the reaction appears to be complete, and allow said mixture to stand for at least one-half hour thereafter in order to insure complete re-- action between the added alcohol and any acid anhydride which may be present. The boiling points of the ester of the lower alcohol and the ester of the nitroalcohol are found to be sufiiciently far apart so that said esters may be satisfactorily separated by fractionation under reduced pressure.

The liquid esters of the nitroalcohols, synthesized as described above from either the aliphatic acid or its anhydride, are obtained in a relatively pure state. However, if additional purification is desired, these compounds may be easily and effectively purified further by careful fractionation under high vacuum, i. e., 1-2 mm. The esters of my invention which are solids under nor-: mal conditions are white crystalline materials having relatively low melting points. Purification of these compounds may be readily effected by recrystallization from a suitable solvent such as benzene.

As examples of acids which can be utilized in the preparation of the esters of my invention, there may be mentioned lauric acid, myristic, oleic. palmitic acid, stearic acid, and the like. In addition anhydrides of the acids of the abovementioned type may also be employed in the production of these new esters. and it is to be under-' stood that said acids and anhydrides function as equivalents in my process.

The nitroalcohols which may be advantageously employed in the preparation of the herein described esters, are represented by the following generic formula:

N 02 H IU-C-JJ-OH methyl-.i-hexanol, 5-nitro-4-octanol, 2-nitro-4-' 3 methyl-3-pentanol, 2-nitro-2,4-dimethyl-3-pentanol, 4-nitro-2,4-dimethyl-3-hexanol, and the like.

The aliphatic nitroalcohols used for the preparation of the above described esters, may be pre- J pared in accordance with any well-known procedures for preparing aliphatic nitrohydroxy compounds. I prefer, however, esters in accordance with the procedure set out in U. S. Patent No. 2,135,144 by B. M. Vanderbilt. According to this process, a primary or secondary nitroparaffin and an aliphatic aldehyde are reacted in the presence of an auxiliary solvent, such as ethyl alcohol, and in the presence of an alkaline catalyst, the aldehyde being added slowly to a solution consisting of the desired nitroparaffin and catalyst in the solvent, with thorough agitation.

My invention may be further illustrated by the following examples which are given by way of illustration only, and the invention is not to be considered as limited thereto.

EXAMPLE I A mixture consisting of 60 parts of 2-nitro-lbutanol, 142 parts of stearic acid, 400 parts of benzene, and 2 parts of concentrated sulfuric acid was heated to reflux temperature and the water formed during the reaction removed as a constant boiling mixture with benzene by distillation through a packed column. When the water ceased to be removed from the reaction mixture in observable amounts, there was added Nitrogen analysis: Calculated for C2zI-I4sO4N:

N, 3.64. Found: 3.63.

EXAMPLE II A mixture consisting of 105 parts by weight of 2-nitro-2-methyl-l-propanol, 206 parts of palmitic acid, 500 parts of benzene and 2 parts of concentrated sulfuric acid was heated to reflux temperature, and there maintained for 8 hours, during which time the water formed during the reaction was removed as a constant boiling mixture with benzene. When water ceased to be removed, the residue was washed with water until free from acid, distilled to remove water and treated with decolorizing carbon and filtered. The filtrate was placed in a refrigerator at about C. whereupon 58.5 parts of a white waxy solid crystallized out. The filtrate was concentrated to 213.6 parts on a steam bath-and allowed to crystallize at room temperature resulting in 49 additional parts of white solid or a total of 107.5 parts of 2-nitro-2-methyl-1-propyl palmitate.

EXAMPLE n A mixture consisting of 540 parts of triple I On cooling, it was transto "prepare these r Then 15 parts of decolorizing carbon was added and refluxing continued for 3 hours, whereupon the mixture was cooled and filtered. The resulting light yellow solution was vacuum distilled,

cooled and 382.8 parts of solid 2-nitro-2-methy1 propyl stearate recovered. The mother liquor was evaporated until free from benzene and an additional 322.8 parts of solid recovered totaling 705.6 parts of 2-nitro-2-methy1 propyl stearate.

The normally liquid esters produced as outlined by the above examples, are water-white materials possessing relatively high boiling points; however, such compounds at atmospheric pressure, on continued heating at their boiling points, are found to decompose slowly. All are soluble in the lower alcohols, as Well as the common aromatic hydrocarbons.

In the process of rendering fabrics water repellent with the compounds of my invention, nitroester is dispersed in a carrier such as benzene or other solvent in a concentration varying with the degree of water repellency desired. Usually a concentration between 5 and 10% will be sufficient to produce the desired water repellency. The fabric is then impregnated with the solution and allowed to dry at room temperature. The water repellency is thereafter developed either by baking in an oven for the desired period at elevated temperature, for example, for about 1020 minutes at 150165 C. or by ironing with a hot iron. Water repellencies of between and '70 rated according to the A. A. T. C. & C. standard spray test in which represents perfect water repellency are obtained which are sub Stantially undiminished after repeated washings.

As illustrative of the water repellency-imparting characteristics of my new compounds, Example IV is given in which a number of these compounds were utilized according to the accepted procedure of the textile trade as impregnants for fabrics, and the resulting water repellencies after baking and ironing respectively, were tested in acordance with the tentative standard spray test of the American Association of Textile Chemists and Colorists as described in the 1941 Yearbook of that association on pages 241 to 245.

EXAMPLE IV Five grams of the nitroester was dissolved in 95 grams of benzene. Two 8-inch squares of cotton toweling (Weight approximately 13 grams, i. e., approximately .38 gram of nitroester per gram of fabric were immersed in the solution long enough to insure thorough penetration. The toweling samples were then drained and allowed to dry in air at room temperature. Thereafter, one of the samples was ironed and the other baked in an oven for 10 minutes at to C. The samples were then tested for waterrepellency by means of a spray tester. Each sample was rated according to a standard chart in which 100 represents perfect water-repellency. After the first test, the samples were washed for one-half hour in 500 cc. of a boiling 0.2 per cent cent soap solution. They were next rinsed thoroughly, dried and tested as before. In certain instances, a second wash treatment was given. Throughout the experiment, distilled water was used.

The results are given in the accompanying table as compared to the chart of standard spray test ratings given on page 244 of the 1941 Yearbook of the American Association of Textile Chemists and Colorists.

TABLE I Water repellency of fabric treated with. nitroester on the basis of standard spray test ratings of A. A. T. C. & 0.

Before Washing After one wash After two washes ESTER Before After After Before After After Before After After ironing ironing baking ironing ironing baking ironing ironing baking Z-Nitro-l-butyl stearate 5 70 0 as 70 o 2-Nitro-2-methyl-l-propyl stearate 0 45 6O 0 65 65 0 40 65 m ate o 45 so 0 0 45 60 2-Nitro-l-propyl stearate 5 55 0 70 0 45 65 2-Nitro-l-butyl acetate 0 0 0 0 0 0 0 0 0 2-Nitro-l-propyl acetate 0 0 0 0 0 0 0 0 0 This case is a continuation-in-part of my co- 20 REFERENCES CITED pending application, U. S. Serial No. 474,337, 1 i f filed February 1, 1943, now abandoned. 5%; 5 g g i f i are 0 record m the While the above describes the preferred embodiments of my invention, it will be understood UNITED STATES PATENTS that departures may be made therefrom within 25 Number m Date the scope of the specification and claim. 2,196,758 Dickey APR 9 1940v What is claimed iSI 2,233,607 Hass Mar. 4, 1941 2-nitro-2-methyl propyl steal-ate suitable fo 2,291,021 Bock et a1 July 28, 19 2 use as waterproofing agents. 30 OTHER REFERENCES JOHN B. TIN'DALL. Vanderbilt: Ind. & Eng. Chemistry, volume 32 (1940), pages 34-38. 

